This prospective, placebo-controlled, double-blind clinical trial evaluated the effectiveness of gabapentin in decreasing subjective features of idiopathic subjective tinnitus in the patients. Pure-tone audiograms, laboratory test and personal histories were used to exclude any particular etiology of tinnitus. Participants were restricted to those with moderate to severe idiopathic subjective tinnitus for at least 6 months. A total of 30 participants received gabapentin in a graduated ascending dose series extending over 4 weeks (peak dose of 900 mg/day). There was not a significant subjective improvement in tinnitus annoyance for the patients (37%) versus controls (42%). Comparison between the results before and after intervention for patients and controls according to subjective response, tinnitus questionnaire, tinnitus severity index and the loudness perception by the patient showed no significant differences (P > 0.05). There is insufficient evidence to support the effectiveness of gabapentin in the treatment of tinnitus up to now.